Note: this really is an RFC. Please don't spend too much time revieweing
the code in detail. I'd like to figure out if that's a good approach at
all first. Also: while I tested it on sm8650-qrd and sc8280xp-crd, the
last patch cannot be applied until all Qualcomm platforms are converted.
Problem: when pinctrl core binds pins to a consumer device and the
pinmux ops of the underlying driver are marked as strict, the pin in
question can no longer be requested as a GPIO using the GPIO descriptor
API. It will result in the following error:
[ 5.095688] sc8280xp-tlmm f100000.pinctrl: pin GPIO_25 already requested by regulator-edp-3p3; cannot claim for f100000.pinctrl:570
[ 5.107822] sc8280xp-tlmm f100000.pinctrl: error -EINVAL: pin-25 (f100000.pinctrl:570)
This typically makes sense except when the pins are muxed to a function
that actually says "GPIO". Of course, the function name is just a string
so it has no meaning to the pinctrl subsystem.
We have many Qualcomm SoCs (and I can imagine it's a common pattern in
other platforms as well) where we mux a pin to "gpio" function using the
`pinctrl-X` property in order to configure bias or drive-strength and
then access it using the gpiod API. This makes it impossible to mark the
pin controller module as "strict".
This series proposes to introduce a concept of a sub-category of
pinfunctions: GPIO functions where the above is not true and the pin
muxed as a GPIO can still be accessed via the GPIO consumer API even for
strict pinmuxers.
The first patch implements this functionality in pinctrl core, the
second adds local infrastructure to pinctrl-msm, next we convert two
Qualcomm platforms as examples and then finally enable the strict flag
in pinctrl-msm.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
Bartosz Golaszewski (5):
pinctrl: allow to mark pin functions as requestable GPIOs
pinctrl: qcom: add infrastructure for marking pin functions as GPIOs
pinctrl: qcom: sm8650: mark the `gpio` pin function as a non-strict function
pinctrl: qcom: sc8280xp: mark the `gpio` pin function as a non-strict function
pinctrl: qcom: make the pinmuxing strict
drivers/pinctrl/pinmux.c | 17 +++++++++++++++--
drivers/pinctrl/qcom/pinctrl-msm.c | 10 ++++++++++
drivers/pinctrl/qcom/pinctrl-msm.h | 5 +++++
drivers/pinctrl/qcom/pinctrl-sc8280xp.c | 2 +-
drivers/pinctrl/qcom/pinctrl-sm8650.c | 2 +-
include/linux/pinctrl/pinctrl.h | 14 ++++++++++++++
include/linux/pinctrl/pinmux.h | 2 ++
7 files changed, 48 insertions(+), 4 deletions(-)
---
base-commit: 1343433ed38923a21425c602e92120a1f1db5f7a
change-id: 20250701-pinctrl-gpio-pinfuncs-de82bd9aac43
Best regards,
--
Bartosz Golaszewski <bartosz.golaszewski@linaro.org>